Question Regarding 'Light' Ammo

[Cagunazrod]

Upfront, Sorry for the 'Newbie' question.

I see ammo for instance '65 Grain+P 9mm Underwood' advertised. I understand the basics of velocity, energy etc.. I see people in reviews commenting that they prefer lighter ammo to keep their loaded EDC pistol lighter when they carry.

My question is, I'm pretty sure I understand that the difference between the 'common' 124 grain and 65 grain bullet is 89 grains (ish) . . . but how does that convert over to ounces or grams ?

Is it really enough of a difference to make a difference, say for instance in 11 rounds of 9mm. I'm also assuming it may be more complicated with the amount /type of powder used etc.

Thanks for any enlightenment, and again I apologize if this is a dumb question.

[edgerly779]

1 1/2 ounce lighter using 65 grain

[TomReloaded]

The weight difference is about 6 quarters (coins).

Light for caliber has poor "sectional density" which means it often fails to penetrate enough to actually stop a person and be effective. 115gr is debatably right on the brink of being too light.

[edgerly779]

1 ounce equals 437.5 grains

[tabascoz28]

Sometimes people want to maximize speed instead of energy, although they are related.

For the example of damaging AR500 steel. A 223 round, 55grains going 3000fps (fast) will not damage steel at 100yards. But load a 22-250 going 4000fps will put a hole through that same steel.

So for protection against bear, where you need to get through some meat to stop it, those lighter but faster bullets along with tip design, will go through to vital organs too, but they will shoot high as heck.

[tabascoz28]

This guy did a test with the 65 and 90 on soft side body armor.

https://www.youtube.com/watch?v=PTnCNx1OTZ0

[ar15barrels]

My question is, I'm pretty sure I understand that the difference between the 'common' 124 grain and 65 grain bullet is 89 grains (ish) . . . but how does that convert over to ounces or grams ?

Is it really enough of a difference to make a difference, say for instance in 11 rounds of 9mm. I'm also assuming it may be more complicated with the amount /type of powder used etc.

7000 grains per pound.
437.5 grains per ounce.

124-65 is 59.
So 11 rounds at 59grains savings per round is 649 grains which is 1.48 ounces.

[Cagunazrod]

Thanks everyone for all the replies. I understand it much better now. There are so many choices nowadays in ammo types, weights, shapes, materials etc. it can be a bit overwhelming. As with most things, it seems that unless I have a specific 'need' or scenario that overall it's probably best to stay with something in the middle or fairly standard, proven and reliable.
Thanks again.

[hermosabeach]

It's pretty simple..... FBI keeps stats on all shootings

#1- shot placement in center of available mass is the goal.

#2 - every 1-3 years some new load is developed that goes viral. Black Rhino and G2 Ammo are the biggest two over hyped rounds


#3 skip hype Ammo (#2 above) and go with proven Ammo. Ammo that will feed in your gun, cycle, extract and eject.

For 9mm- standard 115-147 loads and hopefully a quality hollow point round.


38,357,9mm,.357 sig, .40 and .45 all have about the same effectiveness according to 30+ years of FBI documenting people who were shot and publishing data.

So back to rule #1- get your hits - shoot until the fight is stopped or you can get away. Missing 2-4 times before you get a hit is way slower than getting a hit on the first shot.


If your not happy with your groups at a range, please consider taking a class from a proper instructor or school.



Every pro athlete has a series of coaches.

Shooting is the same
Read a ton of books
Take classes
Practice